Air treating means including an air flow directing system



Filed Aug. 15, 1966 0 0 r 4 1 wzwd mu 5 6 2 wa 4 7 M E M B WM v F. m E k[M z I4 [-4 MA- I z. N w 6 e 0 MN N 6 6 40 N 7 0 6 s P 10 8 Y 6 w 0. 3 B7 6 a Z 0 Z 2 z 4. w a 2 o m, I 2 a 8 u. MA x G A. 7 s 2 A L I \H w WNAM F III. E 1|: 4 i i flm n m G. HESKESTAD ET AL June 11, 1968 AIRTREATING MEANS INCLUDING AN AIR FLOW DIRECTING SYSTEM FIE-E UnitedStates Patent 3,387,647 AER TREATING MEANS INQLUDENG AN AIR FLOWDIRECTING SYSTEM Gunnar l-Ieskcstad, 34 Seymour Terrace, Piscataway, NJ.

08854, and Daniel Gordon Galiie, 6757 (Iortiand, Aiien Park, Mich. 48101Filed Aug. 15, 1966, Ser. No. 572,384 16 Claims. (Cl. 16532) ABTRAT OFTHE DESCLQSURE An air treating means comprising two heat exchange coilsarranged in parallel flow relation (side-by-side in the air duct). Airis admitted to the coil faces through a small inlet duct, and isdirected to one or the other coil by boundary layer control devices.Each control device comprises an air extraction mechanism arranged towithdraw a minor amount of air from the main stream boundary layer as itpasses from the small inlet duct into the larger duct containing theheat exchange coils. By controlling the amount of air withdrawn from therespective portions of the boundary layer we expect to control or directthe main stream.

This invention relates to commercial and industrial air conditioningsystems, including those under development for future passengervehicles, having the heating and cooling coils in parallel flowrelationship. In such systems dampers are often used to regulate thevolume of air treated by each of the coils in response to the moistureand temperature requirements of the environment being conditioned.During service, air is conveyed to the coils through ducts at arelatively high velocity for the purpose of conserving space andmaterial. Before entry into the coils, the air is reduced to arelatively low velocity in order to provide more efiective treatment ofthe air over the coil surface.

In many systems the space between the supply duct and the coils isoccupied by a flaring difiuser duct that is shaped with an increasingcross-sectional area in the direction of air flow. The purpose of thediffuser duct is to expand the air by having it occupy all of the ductcross-sectional area as it moves through the diffuser, and thereby bedecelerated to a lower velocity at the diffuser outlet. The length ofthe diffuser must be sufficient to provide for complete expansion;otherwise the air will separate from the diifuser walls and expand atless than the required rate. Whenever there is incomplete expansion, aportion of the coil face does not come into contact with the air streamand greater velocities than intended exist at the coil, causing higherflow resistance.

As a corrective measure to the heat transfer problem, additional coilcapacity is sometimes used in order that the part of the coil exposed tothe air stream can properly carry the thermal load. Additional coilcapacity is made available by increasing the fin density and the coilthickness, or by using either of the two methods separately. The neteffect of moving air through a coil of increased capacity is additionalflow resistance necessitated by incomplete expansion, which by itselfincreases the flow resistance. Abbreviated diffusers may be said toimpart the following penalties:

(a) Necessitate the use of a coil with increased thermal capacity havingadded size, weight, and cost.

(b) Necessitate the use of a fan with increased pressure capacity,requiring more power and creating additional noise.

(c) Necessitate the use of a higher capacity fan drive mechanism andmotor.

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In spite of the above penalties economics requires that the diffuserlength be as abbreviated as possible to limit material and spacerequirements. Thus, a penalty is usually imposed on the performance ofthe system as a result of the abbreviated diffuser which is commonlyused.

The present invention seeks to eliminate the flaring diffuser sectionand dampers generally found necessary under prior art practice. Inaccomplishing this result we employ air extraction mechanisms at thejuncture between the blower discharge and the downstream duct leading tothe heat exchange coils. The air extraction mechanisms are arranged todraw portions of the air stream around the corner between the blowerdischarge duct and transition wall leading to the large duct containingthe heat exchange coils; the air draw-off action is such as to cause themain stream to become attached to the tran sition wall and morecompletely diffuse into all areas of the larger duct. Certain airdischarge mechanisms may be arranged to exert a blowing actiontransverse to the main air stream, to thus cooperate with the airextraction mechanisms in obtaining directional control of the mainstream. Selector valves may be employed to selectively energize the airextraction mechanisms and air discharge mechanisms, whereby the main airstream is caused to be selectively diverted through the heating coil orcooling coil.

This invention suggests the application of the air extraction effect,with or without the blowing effect, to derive the following advantages:

(a) Regulating the quantity of air through either coil.

(b) Expanding the air over the entire coil face.

(0) Minimizing flow losses through the transition duct and coil.

(d) Reducing floor space and duct length.

The air extraction principle exercises an influence on a central airstream such that when air is moving through a shortened diffuser with astepped shape (expanding wall of diffuser is normal to direction of airflow), the air stream will deviate from its normal flow path. The amountof deviation is dependant on the width and angle of inclination of thesuction slots and on the volume of air extracted through the slotslocated in the walls of the duct. The slots are typically inclined at anangle of 45 with the upstream Wall; they have a width equal to 3% of thesmallest cross-sectional linear dimension of the approach duct, and arelocated immediately upstream of the step in the diffuser. I

Winter operation of a parallel coil system requires that the amount ofair passing through the heating coil is varied in accordance with theload. Unheated air is bypassed through the cooling coil which isinoperative, and thereupon mixes with air from the heating coil insatisfying load requirements. Replacement of the conventional damperswith air extraction or suction slots should reflect improvements beyondthe mode usually employed for winter operation. The air extraction slotswould divert only as much of the air through the heating coil asnecessary in fulfilling load requirements. When most of the air is beingdiverted through the heating coil, it is expected that the deflectingaction of the air extraction slot may be supported by injecting orblowing air into the slot located on the duct wall opposite the heatingcoil. The air in jection technique is employed in this invention todeflect the portion of the main air stream that is least influenced bythe slot action.

During milder weather as the demand for heat is diminished, less airwould be diverted through the heating coil. The amount of air beinginjected through the slot into the main stream on the cooling coil sideof the duct would be decreased; that slot would commence to extract airfrom the main stream with increased demand for cooling. Thus, a greaterquantity of the main air stream would be directed to the cooling coil,and with the cooling coil becoming operational, air conditionin"requirements would be satisfied.

in addition to the demand for cooled and dehumidified air during summeroperation, heated air is essential for tempering the air to satisfyrequirements after the cooling and moisture separating process hasoccurred in the cooling coil. During this phase, all of the air would bedirected through the cooling coil with maximum air extraction occurringthrou h the slot on the cooling coil side of the duct, and maximum airinjection into the main stream through the slot on the opposing ductwall. A heating coil would be located in a downstream position to temperthe conditioned air at the necessary rate.

Under conventional methods the rapid expansion of air, together withdeflection toward one of two coils is usually an inefficient process.The action is conventionally improved by replacing a highly divergentdiffuser with one of extended length and a lower rate of wall divergence. However, as suggested in the present invention, rapid expansionof air through a stepped diffuser equipped with suction slots is asefficient in recovering pressure as the conventional diffuser ofextended length. Moreover, the new slotted diffuser represents addedeconomy in terms of floor space and duct cost.

Other savings are reflected in the heating and cooling coil cost whereless fin surface is necessary in providing an equivalent thermalcapacity. This is due to the more complete coverage of air across thecoil face, with the entire coil surface being effective in transferringheat at maximum coil loading. Similarly, with flow occurring through alarger area of the coil face, the air velocity diminishes due to themore complete coverage across the face. The combination of a lower facevelocity and less fin surface represents a reduction in air flowresistance through the coil, resulting in reduced fan input horsepower.

Elimination of dampers from he coil face excludes the need for dampermotors and connecting linkage. For the larger installations, the dampermotors require considerable torque capacity and incur added expense. Itis expected that the new suction slot arrangement will be less expensivecompared with conventional systems.

One object of the present invention is to provide improved means forregulating the flow of air through either coil in a multi-coil airtreating arrangement.

Another object is to provide improved means for causing an air stream toundergo a smooth controlled expansion as it moves from a relativelysmall duct into a larger duct.

Another object is to minimize energy losses due to turbulence as an airstream moves from a small duct into a larger duct.

A further object is to provide an air treating means of the dual coiltype wherein both coils are as small as possible, as regards size,weight and cost.

An additional object is to provide an air treating mechanism having afan and duct system of improved pressure capacity and sound-emittingcharacteristics.

An additional object is to provide an air treating mechanism occupyinglesser space than corresponding prior art systems.

A further object is to provide an air treating mechanism wherein a fandischarges a highly diffused air stream directly into one or more heatexchange coils without the necessity of intervening louvers or dampersto provide directional control.

In the drawings:

FIG. 1 is a sectional view taken through an air treating meansconstituting one embodiment of the invention.

FIG. 2 is a transverse sectional view taken on line 2-2 in FIG. 1.

FIGS. 3 and 4 are fragmentary sectional views of portions of two ducts,showing the flow pattern therein.

Referring more particularly to the drawing, there is shown an airtreating means comprising a large rectangular air duct l6 having abottom wall 12, side walls 14 and i6, and top wall 18. Extending acrossduct 1% is a transverse wall 2! separating the duct into an upstreamportion 22 and a downstream portion 24. in service, air in duct portion22 is drawn into the conventional centrifugal blower housing 26, whichis preferably of the double inlet type and equipped with a conventionalfan wheel 28 having forwardly curved blades. The conventional centerplate 3% of the wheel is arranged to be rotated within housing 26 by anexternal motor (not shown) whereby to draw the air into the wheelthrough the housing inlet eyes .32 and The air is discharged from thewheel into a rectangular duct 36 having a top wall 38, bottom wallii-3*, and side walls 42 and 44-. The air at a relatively high pressure,as for example eight inches water gage static pressure, flows leftwardlyout of duct 36 into the larger duct section rranged within the upperportion of duct section 24 is a heating coil 53 of the two row typehaving heat exchange fins 45 extending parallel to the duct side walls14 and 16. Hot fluid such as water at about 200 F. may be supplied tocoil 43 to heat the air as it passes between the fins 45. Arrangedwithin the lower portion of duct section 24 is a cooling coil 46 havingfins 48 extending parallel to side walls 14 and 16. Cold fluid such aswater having an entering temperature of 45 F. may be supplied to coil 46to cool the air passing between fins 48.

It will be noted that the distance between duct 36 and the enteringfaces of the fins 45 and 48 is advantageously relatively small, being onthe order of one diameter or width of duct 36. Unless specialprecautions are taken the air discharged from duct 36 will tend to passthrough the coil portions in direct alignment with duct 36, i.e. theupper portions of coil 46 and the lower portions of coil 43. Little orno air will flow through the lower portions of coil 46 or the upperportions of coil 43. This invention proposes a special control mechanismto provide a more even velocity distribution across the entering facesof the coils.

As shown in the drawing, the control mechanism comprises an airextraction mechanism comprising two air manifolds 5t} and 52. Manifold56 extends across the width of wall 38 and halfway down side walls 42and 44. Manifold 52 extends across the full width of duct wall 40 andupwardly halfway along each side wall 42 and 44. End walls or partitions54 close and separate the respective manifolds. The general arrangementis such that manifold 50 extends about the upper half of the perimeterof duct 36 and manifold 52 extends about the lower half of the perimeterof duct 36. The manifolds do not connect with one another in a fluidsense.

Manifold 50 communicates with the main air stream through a slot 56which preferably extends substantially the entire length of the manifoldat the corner between duct 36 and transverse wall 20. One or morecontrol ducts 58 lead from manifold 50 to a control valve 66 having avalve element 62 seated on a lower seat 64 when solenoid 66 is in thetie-energized condition. When the solenoid is energized the conventionalarmature plunger 68 is raised to move element 62 from seat 64 onto upperseat 70. A flow path is thus provided between control duct 58 and asecond control duct 72.

Duct '72 includes an open end 73 extending into the inlet eye 32 of thefan 26. Therefore when the fan is operating the wheel 23 induces a flowof air through duct 72 in the arrow '74 direction. This air in turndraws air through duct 58 in the arrow 76 direction, which in turnextracts air from manifold 50. The manifold air is in turn replaced withair drawn through slot 56. This extraction of air through slot 56 hasbeen found to minimize the separation which would otherwise occur alongthe downstream face of wall 20.

FIGS. 3 and 4 illustrate the general flow pattern, with and without theair extraction mechanism. As shown in FIG. 3, the air continuesundeflected into the enlarged duct 24a, the space immediately adjacentduct wall 18a having nearly stagnant fluid. When air extractionmechanism St is used the air tends to fill the enlarged duct.

Apparently the air extraction slot 56 tends to deflect the main airstream around the corner between duct 36 and wall 20. A limitedseparated Zone 78 exists in the corner of walls 18 and 20. Beyond thiszone the air stream has diffused so that it substantially completelyfills the large duct section 24. The air in effect undergoes a smoothcontrolled expansion with a minimum of turbulence which would otherwisebe expected with the abrupt increase in duct dimension provided bytransverse wall 26'. Preferably, suction slot 56 faces the downstreamduct area, with the plane of the slot having an angle of about 45degrees with respect to the walls of duct 36. The width of slot 56 ispreferably between 1% and of the width of upstream duct 36.

In some cases the air-extracting effect of slot 56 may be enhanced byblowing air transversely across duct 24. There are therefore providedtwo additional manifolds 8t) and 82. Manifold 80 extends across the fullwidth of duct wall 18 and halfway down the sidewalls l4 and 16. Manifold82 extends across the full width of duct bottom wall 12 and halfway upthe sidewalls 14 and 16. The ends of the manifolds are closed bypartitions 84. Thus, it will be seen that manifold 80 occupies the upperhalf of the perimeter of duct section 24, and manifold 82 occupies thelower half of the perimeter of duct section 24. Each manifold isprovided with an air injection or discharge slot 86 or 88 preferablyextending substantially the full length of the respective manifold.

As shown in FIG. 1, manifold 89 communicates with a control duct 90leading to valve 69. In the illustrated position of valve element 62, apilot-fluid control path is provided by manifold 80, duct 99, valve seat70, duct 58, and manifold 59'. When fan 26 is operating the staticpressure in duct 24 adjacent slot 86 may be relatively high. Assumingthe pressure at 86 is higher than the pressure at 56, with valve element62 in the illustrated position air from duct section 24 would flow intomanifold 89, through duct 90 in the arrow 92 direction, across valveseat '79, into control duct 58 and eventually out through slot 56. Theair blowing out of slot 56 would attempt to deflect the main air streamdownwardly toward coil 46. In some systems the pressure difierentialmight not be obtained, and the blowing effect could not be realized.

When solenoid 66 is energized to move valve 62 onto seat 70 a new pilotfluid control path is provided. This new path includes slot 56, manifold50, duct 58, seat 64, and duct 72. Flow through this path in the arrow74 direction will cause the main air stream to lock onto the downstreamface of transition wall 20 and diffuse transversely as previouslydescribed.

The control duct system for manifolds 52 and 82 is preferably the sameas the control duct system for manifolds 50 and 80; hence similar primednumerals are employed. In each case the control may be triggered by asolenoid 66 or 66. Solenoid 66 may be energized by a conventional roomthermostat or ductstat responding to temperature or humidity conditionsin the spaces being treated by the air treating apparatus. The heatingthermostat is shown schematically in FIG. 1 as a snap switch 94 adaptedto have its contacts opened and closed by a bimetal actuator 96. Asimilar cooling thermostat may be used to control solenoid 66'.

The solenoid valves and their controls may be so arranged that on thecall for heat slot 56 functions as an air extraction slot while slot 57functions as an air blowing slot. On the call for cooling slot 56 shouldfunction as a blowing slot and slot 57 as a suction slot. The suctioneffect is decidedly the predominating effect, and with certain coildimensions the blowing operation may be eliminated or unobtainable. Inthat event the 3-way valves 60, 60' and air discharge manifolds 80, 82may be eliminated in favor of simple 2-way valves connected between ductsections 90, and 72, 72. The illustrated fully open fully closed valves60, 60' may be replaced with more expensive motor-operated modulatingvalves if more precise directional control of the main stream isdesired. Instead of two separate valves 60 and 60' there may be employeda single multi-passage valve of the selector type programmed to providethe desired pilot-control action.

As illustrated, the inlet side of the system supply fan may be used as asuitable suction source for achieving a satisfactory air extractionaction. Alternately a small vacuum pump driven by the supply fan motoror an auxiliary motor may be employed. A water or air-powered jet pumpmight also be used as a suction source. Under some circumstances the airextraction action could be controlled by controlling the auxiliary pumpor suction source; this would be an alternative to valves 60' and 60.

It will be seen that with the described use of air suction or extractionthe general objects of the invention are attained, namely regulation ofair flow through either coil in a multi coil arrangement, a smoothnon-turbulent expansion of the air as it moves from small duct 36 intolarger duct 24, a uniform face velocity across each coil, a possiblereduction in coil size and cost, the elimination of louvers or dampersbetween the blower and coils, and a reduction in diliuser length.

We claim:

1. Air treating means comprising a relatively small inlet duct; arelativley large outlet duct; a transition wall connecting said ducts toprovide a transverse expansion of the air stream as the air flows intothe outlet duct; first and second heat exchange coils arrangedrespectively in different spatial portions of the outlet duct inparallel flow relation with one another; a first air extractionmechanism arranged to withdraw a minor amount of air from one boundarylayer portion of the air stream as it passes into the outlet duct, tothus draw the air stream toward the first heat exchange coil; a secondair extraction mechanism arranged to withdraw a minor amount of air fromanother boundary layer portion of the stream as it passes int-o theoutlet duct, to thus draw the air stream toward the second heat exchangecoil; and control means operable to regulate the air flow rates throughindividual ones of said first and second air extraction mechanismswhereby to apportion the flow between the heat exchanger coils.

2. The air treating means of claim 1 and further comprising a suctionsource; said control means comprising first and second valved controlpassages extending between respective ones of the air extractionmechanisms and the suction source.

3. The air treating means of claim 1 wherein the control means comprisesvalve means controlling flow through the air extraction mechanisms, andautomatic means responsive to conditions within the area serviced by thetreating means for controlling the valve means.

4. The air treating means of claim 1 and further comprising acentrifugal fan arranged upstream from the inlet duct to supply a streamof air thereto; said control means comprising first and second valvedcontrol passages extending from respective ones of the air extractionmechanisms to the fan inlet, whereby said fan constitutes a suctionsource for the extraction mechanisms.

5. The air treating means of claim 1 wherein the control means isoperable to inversely vary the relative flows through respective ones ofseparate control ducts communicating with individual air extractionmechanisms.

'6. The air treating means of claim 1 wherein the inlet duct has arectangular cross section, the cross sectional width and length of theinlet duct being less than the corresponding cross sectional width andlength of the outlet duct, whereby the air undergoes a two-dimensionalexpansion as it flows into the outlet duct.

7. The air treating means of claim 1 wherein the first air extractionmechanism comprises a manifold extending around approximately one halfof the perimeter of the inlet duct at its juncture with the transitionWall, and the second air extnaction mechanism comprises a secondmanifold extending around approximately the remaining one half of theperimeter of the inlet duct at its juncture with the transition wall.

8. The air treating means of claim 1 and further comprising a first airdischarge mechanism arranged downstream from the transition walladjacent a perimetrical portion of the first heat exchange coil; asecond air discharge mechanism arranged downstream from the transitionwall adjacent a perimetrical portion of the second heat exchange coil; asuction source; said control means including structure operable toselectively connect each air extraction mechanism with its respectiveair discharge mechanism or suction source, whereby in one condition ofthe control means air may flow from a given discharge mechanism into itsrespective air extraction mechanism to exert a blowing action on themainstream, and in another condition of the control means air may flowfrom the respective air extraction mechanism to the suction source toexert a suction action on the mainstream.

9. The air treating means of claim 8 wherein the control means includesa three-way valve, a first control duct extending between an airextraction mechanism and one chamber of the valve, a second control ductextending between an air discharge mechanism and another chamber of thevalve, and a third control duct extending between the suction source anda third chamber of the valve, said valve including a first valve seatbetween the first and second chambers and a second valve seat betweenthe first and third chambers.

10. The air treating means of claim 1 wherein the transition Wallextends substantially normal to the duct axis.

References Cited UNITED STATES PATENTS 2,052,869 9/1936 Coanda 230122 XR2,191,224 2/1940 Adair 165-126 XR 2,284,764 6/1942 Parks 165-27 XR2,303,094 11/1942 Sharpe 16527 XR 2,344,835 3/1944 Stalker 230-4222,894,728 7/1959 Davis 165126 XR 2,944,729 7/1960 Foley et al 230-l22ROBERT A. OLEARY, Primary Examiner.

M. A. ANTONAKAS, Assistant Examiner.

